lib/web/grab_to_pan.js

/**
 * @licstart The following is the entire license notice for the
 * Javascript code in this page
 *
 * Copyright 2020 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @licend The above is the entire license notice for the
 * Javascript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.GrabToPan = GrabToPan;

function GrabToPan(options) {
  this.element = options.element;
  this.document = options.element.ownerDocument;

  if (typeof options.ignoreTarget === "function") {
    this.ignoreTarget = options.ignoreTarget;
  }

  this.onActiveChanged = options.onActiveChanged;
  this.activate = this.activate.bind(this);
  this.deactivate = this.deactivate.bind(this);
  this.toggle = this.toggle.bind(this);
  this._onmousedown = this._onmousedown.bind(this);
  this._onmousemove = this._onmousemove.bind(this);
  this._endPan = this._endPan.bind(this);
  const overlay = this.overlay = document.createElement("div");
  overlay.className = "grab-to-pan-grabbing";
}

GrabToPan.prototype = {
  CSS_CLASS_GRAB: "grab-to-pan-grab",
  activate: function GrabToPan_activate() {
    if (!this.active) {
      this.active = true;
      this.element.addEventListener("mousedown", this._onmousedown, true);
      this.element.classList.add(this.CSS_CLASS_GRAB);

      if (this.onActiveChanged) {
        this.onActiveChanged(true);
      }
    }
  },
  deactivate: function GrabToPan_deactivate() {
    if (this.active) {
      this.active = false;
      this.element.removeEventListener("mousedown", this._onmousedown, true);

      this._endPan();

      this.element.classList.remove(this.CSS_CLASS_GRAB);

      if (this.onActiveChanged) {
        this.onActiveChanged(false);
      }
    }
  },
  toggle: function GrabToPan_toggle() {
    if (this.active) {
      this.deactivate();
    } else {
      this.activate();
    }
  },
  ignoreTarget: function GrabToPan_ignoreTarget(node) {
    return node[matchesSelector]("a[href], a[href] *, input, textarea, button, button *, select, option");
  },
  _onmousedown: function GrabToPan__onmousedown(event) {
    if (event.button !== 0 || this.ignoreTarget(event.target)) {
      return;
    }

    if (event.originalTarget) {
      try {
        event.originalTarget.tagName;
      } catch (e) {
        return;
      }
    }

    this.scrollLeftStart = this.element.scrollLeft;
    this.scrollTopStart = this.element.scrollTop;
    this.clientXStart = event.clientX;
    this.clientYStart = event.clientY;
    this.document.addEventListener("mousemove", this._onmousemove, true);
    this.document.addEventListener("mouseup", this._endPan, true);
    this.element.addEventListener("scroll", this._endPan, true);
    event.preventDefault();
    event.stopPropagation();
    const focusedElement = document.activeElement;

    if (focusedElement && !focusedElement.contains(event.target)) {
      focusedElement.blur();
    }
  },
  _onmousemove: function GrabToPan__onmousemove(event) {
    this.element.removeEventListener("scroll", this._endPan, true);

    if (isLeftMouseReleased(event)) {
      this._endPan();

      return;
    }

    const xDiff = event.clientX - this.clientXStart;
    const yDiff = event.clientY - this.clientYStart;
    const scrollTop = this.scrollTopStart - yDiff;
    const scrollLeft = this.scrollLeftStart - xDiff;

    if (this.element.scrollTo) {
      this.element.scrollTo({
        top: scrollTop,
        left: scrollLeft,
        behavior: "instant"
      });
    } else {
      this.element.scrollTop = scrollTop;
      this.element.scrollLeft = scrollLeft;
    }

    if (!this.overlay.parentNode) {
      document.body.appendChild(this.overlay);
    }
  },
  _endPan: function GrabToPan__endPan() {
    this.element.removeEventListener("scroll", this._endPan, true);
    this.document.removeEventListener("mousemove", this._onmousemove, true);
    this.document.removeEventListener("mouseup", this._endPan, true);
    this.overlay.remove();
  }
};
let matchesSelector;
["webkitM", "mozM", "msM", "oM", "m"].some(function (prefix) {
  let name = prefix + "atches";

  if (name in document.documentElement) {
    matchesSelector = name;
  }

  name += "Selector";

  if (name in document.documentElement) {
    matchesSelector = name;
  }

  return matchesSelector;
});
const isNotIEorIsIE10plus = !document.documentMode || document.documentMode > 9;
const chrome = window.chrome;
const isChrome15OrOpera15plus = chrome && (chrome.webstore || chrome.app);
const isSafari6plus = /Apple/.test(navigator.vendor) && /Version\/([6-9]\d*|[1-5]\d+)/.test(navigator.userAgent);

function isLeftMouseReleased(event) {
  if ("buttons" in event && isNotIEorIsIE10plus) {
    return !(event.buttons & 1);
  }

  if (isChrome15OrOpera15plus || isSafari6plus) {
    return event.which === 0;
  }

  return false;
}